The present invention relates to a generator-starter system for a multi-shaft engine with a generator coupled to the high-pressure shaft of the high-pressure turbine for taking off a high electric power and for starting the engine.
Secondary electric power, as is generally known, is today pneumatically taken off the engine. If the electrical power demand of the aircraft is high, such a generator-starter arrangement is, however, disadvantageous in that the compressor encounters stability problems when power take-off is very high and the higher weight resulting from the increased performance of the generator, which also acts as motor during engine start, affects the distribution of weight on the engine. Therefore, the electric power supply is limited.
Further known is the off-take of the required electric power by way of a generator connected to the low-pressure shaft, an arrangement which, however, necessitates a complex gearbox since the speed of the low-pressure shaft is variable. Furthermore, the generator, which is connected to the low-pressure shaft, cannot be used as starter for the engine, and a clutch, which would in this arrangement be required between the high-pressure and the low-pressure shaft, is complex and increases weight.
Finally, the use of so-called “embedded” generators was proposed which, however, are badly accessible and, therefore, entail considerable maintenance and repair effort.